Let me tell you now about a photo from that day back in May 2011 when Osama bin Laden was killed by a team of Navy SEALs. It was taken here in Washington inside the White House Situation Room. And it shows a guy in a button-down brown shirt briefing President Obama and his national security team as the raid unfolded.

NICK RASMUSSEN: And I was the recipient a minute before of some information. And so I was in the position of having to say, wait a minute, I have information everybody needs to hear, and standing up and asking everybody to stop for a second so I could tell them something that I had been told by one of our intelligence collecting agencies.

KELLY: That's the voice of Nick Rasmussen, the guy in the photo. Rasmussen has advised three presidents now on terrorists and how to stop them. He is the nation's most senior terrorism analyst - at least for now. He steps down on December 22 as director of the National Counterterrorism Center. And since that photo was taken, Rasmussen told me he has watched as attention shifted from al-Qaida to ISIS and homegrown threats.

RASMUSSEN: What I've concluded over time is that the traditional tools of intelligence and law enforcement that we used to such great effect after 9/11, those were terrific tools and served us very, very well in dealing with that al-Qaida threat. The tools that I think we need to focus on now here in the homeland are much more community-based tools. They need to understand how these terrorist tactics could play out in their communities. Also, we need to engage with communities across the United States to help them understand how young people get radicalized. How does an individual move from simply being a consumer of extremist material to the point where they'll actually do something like drive a car down a pedestrian sidewalk?

KELLY: Sidewalk in Manhattan, yeah.

RASMUSSEN: And the answer is that there's a process that that person goes through. And that process, unfortunately, now is accelerated by the person's access to all kinds of extremist material.

KELLY: The flash to bang ratio. That's what you call it.

RASMUSSEN: Exactly. One of the studies we conducted at NCTC concluded that of the homeland attacks here in the United States, almost 80 percent of them involved some bystander who in retrospect said, wow, I thought that person might have been headed down a terrible path and I wasn't sure or I didn't do something about it. Our job is to empower people to act on that information in a way that interrupts that cycle before it happens.

KELLY: We've been talking about how you see the threat. What about where you see it? When you look at a map of the world now or the U.S., what areas light up?

RASMUSSEN: In the aftermath of 9/11 when al-Qaida was our principal concern, we worried a lot about big metropolitan cities, big iconic targets - the Statue of Liberty.

KELLY: Brooklyn Bridge.

RASMUSSEN: The Brooklyn Bridge. And so a lot of time and attention was spent on hardening targets, iconic targets. What ISIS has shown us is that they can gain similar acceleration for their cause by going after soft targets - pedestrians on a street. So I think one of the things we've learned is that there really is no geographic fence around this. This is just as likely to occur in a rural or suburban location as in a metropolitan location. Looking globally, though, ISIS at its core and its heart in its so-called caliphate in Iraq and Syria, they now have networks and branches that exist across the globe.

KELLY: President Trump tweeted recently anti-Muslim videos. Is that helpful as you are trying to work with global partners and build sources in Muslim capitals around the world and communities here in the U.S.?

RASMUSSEN: You know, I have a really hard time kind of isolating any one event on any one day and saying whether something is helpful or it advances the cause. But what I do know is that the set of partnerships we need not just with Muslim-majority countries but with Muslim communities here in the United States, with partners all around the world who watch what we do, who want to align with the United States in the effort to prevent terrorism, we ought to do everything we can not to make that more difficult. And anything we do that undermines their ability to help is something I would want to avoid.

KELLY: Does it make that process more difficult to have a U.S. president who is tweeting anti-Muslim videos, who is pitching a travel ban that would block visitors from certain Muslim countries, who's in a Twitter war with the Muslim mayor of London?

RASMUSSEN: Again, hard for me to judge in terms of how the politics of any particular policy moved by this president or any administration affects the global environment. What I do know is that in the cooperation that we enjoy intelligence professionals to intelligence professionals, we tend not to be bothered or affected by that kind of - by that kind of activity.

KELLY: Nick Rasmussen, what's next?

RASMUSSEN: I honestly don't know. I will probably take some time starting in January to figure out what I want to do. I know I'm going to want to stay involved in the debate. I will want to stay involved in national security issues.

KELLY: Spy novel in your future?

RASMUSSEN: There's no spy novel in my future. I enjoy a good spy novel. I'm not sure I'm capable of writing one.

KELLY: Well, we wish you luck in your future endeavors. Nick Rasmussen. He steps down later this month after three years as director of the National Counterterrorism Center. Thanks for coming by.